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Marshal.PtrToStringAuto Method (IntPtr, Int32)

Copies a specified number of characters from a string stored in unmanaged memory to a managed String.

Namespace: System.Runtime.InteropServices
Assembly: mscorlib (in mscorlib.dll)

public static string PtrToStringAuto (
	IntPtr ptr,
	int len
public static String PtrToStringAuto (
	IntPtr ptr, 
	int len
public static function PtrToStringAuto (
	ptr : IntPtr, 
	len : int
) : String



For Unicode platforms, the address of the first Unicode character.


For ANSI plaforms, the address of the first ANSI character.


The number of characters to copy.

Return Value

A managed string that holds a copy of the native string if the value of the ptr parameter is not a null reference (Nothing in Visual Basic); otherwise, this method returns a null reference (Nothing in Visual Basic).

Exception typeCondition


len is less than zero.

On Unicode platforms, this method calls PtrToStringUni; on ANSI platforms, it calls PtrToStringAnsi. No transformations are done before these methods are called.

PtrToStringAuto is useful for custom marshaling or when mixing managed and unmanaged code. Since this method creates a copy of the unmanaged string's contents, you must free the original string as appropriate. PtrToStringAnsi provides the opposite functionality of Marshal.StringToCoTaskMemAuto and Marshal.StringToHGlobalAuto.


This method uses SecurityAction.LinkDemand to prevent it from being called from untrusted code; only the immediate caller is required to have SecurityPermissionAttribute.UnmanagedCode permission. If your code can be called from partially trusted code, do not pass user input to Marshal class methods without validation. For important limitations on using the LinkDemand member, see Demand vs. LinkDemand.

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0